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Date:      Thu, 12 Mar 2009 11:24:32 +0100
From:      Tijl Coosemans <tijl@ulyssis.org>
To:        freebsd-hackers@freebsd.org
Cc:        octavian.covalschi@gmail.com, Alexander Motin <mav@freebsd.org>, Daniel Thiele <dthiele@gmx.net>
Subject:   Re: Spin down HDD after disk sync or before power off
Message-ID:  <200903121124.33358.tijl@ulyssis.org>
In-Reply-To: <49B04281.2030406@gmx.net>
References:  <200903041938.n24Jcqdr060153@lurza.secnetix.de> <49AF9381.50709@FreeBSD.org> <49B04281.2030406@gmx.net>

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On Thursday 05 March 2009 22:22:09 Daniel Thiele wrote:
> Looking at the numbers in the Hitachi drive specifications Tobias an I
> dug out from the Hitachi website (see replies in the Joerg Sonnenberger
> branch of this thread) the normal Load/Unload count is about 30 times
> higher than the Emergency Unload count. So even if an
> ATA_STANDBY_IMMEDIATE command may introduce additional Load/Unload
> stress on reboot it is not as bad as the stress causes by an Emergency
> Unload on shutdown. Of course this only applies if the "click" sound is
> really caused by an Emergency Unload. Is there a way to figure out?
> Maybe the S.M.A.R.T. feature records the two kinds of power-offs.

Emergency Unload is called Power-Off_Retract_Count in SMART output.



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